1. MuCool Test Area http://mice.iit.edu/mta/
Dedicated facility built at the end of the Linac to address MuCool needs
RF power 805MHz, 201MHz)
Large-bore 5T superconducting solenoid
Cryogenic plant
400-MeV H- beamline
Class-100 portable clean room
Hydrogen safety infrastructure
805- and 201-MHz cavities
Radiation detectors
June 27, 2017
Alan Bross | MICE cm48, Belgrade

2. Alan Bross | MICE cm48, Belgrade
MTA Diagnostics
RF directional coupler and pickup signals
Vacuum pressure
Scintillator+PMT counters for X-ray rates, spectra
Ionization chambers for radiation dose rates
Spectrometer for cavity light analysis
Thermocouples for cavity temperature
Acoustic sensors for spark detection (under development)
Toroids for beam intensity
BPM, MW and scintillator for beam profile/position
Environmental monitoring
June 27, 2017
Alan Bross | MICE cm48, Belgrade

3. Vacuum Pillbox Cavity R&D 805-MHz Modular Cavity (SLAC/LBNL)
Latest R&D vehicle for detailed systematic studies
Modular design for easy assembly, parts replacement
Removable endplates (Cu, Be, TiN coated surfaces)
Coupling iris moved to center ring and field reduced (more realistic design)
RF design validated by detailed simulation
Ports for instrumentation
June 27, 2017
Alan Bross | MICE cm48, Belgrade

4. Modular Cavity Program
Microscope setup in clean room for detailed endplate inspection after every run
Allowing us to keep track of surface features
Breakdown study Ph. D. project for Alexey Kochemirovskiy (U. Chicago)
Supervisor Daniel Bowring
June 27, 2017
Alan Bross | MICE cm48, Belgrade

5. Modular Cavity: Cu endplates
B=0 T, Apr-Oct 2015
13M pulses, 130 sparks, 45 MV/m
B=3 T, Dec 2015
5M pulses, 55 sparks, <12 MV/m
B=0 T, Jan-Feb 2016
14M pulses, 460 sparks, 22 MV/m
B=3 T, Apr 2016
3M pulses, 81 sparks, ~10 MV/m
June 27, 2017
Alan Bross | MICE cm48, Belgrade

6. Inspection after B=0 run
~500 documented spots on surface
look relatively flat
No correlation between opposing endplates
Representative features below
June 27, 2017
Alan Bross | MICE cm48, Belgrade

7. Inspection after B=3T run
168 spots on surface
Clearly visible damage, qualitatively different structure
B=3 T
June 27, 2017
Alan Bross | MICE cm48, Belgrade

8. Inspection after B=3T run
Perfect matching between endplates
Radial distribution consistent with E-field pattern
June 27, 2017
Alan Bross | MICE cm48, Belgrade

9. Modular Cavity: Be endplates
Results PRELIMINARY
Be+Be, B=3 T, Apr 2017
11M pulses, 160 sparks, 37 MV/m
Be+Be, B=0 T, Apr 2017
80k pulses, 1 spark, 37 MV/m
Be+Cu, B=3 T, May-Jun 2017
13M pulses, ~40 sparks
June 27, 2017
Alan Bross | MICE cm48, Belgrade

10. Alan Bross | MICE cm48, Belgrade
Status/schedule
Next Modular Cavity run starting this week
Be endplates in several B-field settings
To be completed Jul 14
Fermilab accelerator complex maintenance period starts Jul 7
Disassembly, inspection afterward
End of MTA program
decommissioning before Oct
future use of facility TBD
June 27, 2017
Alan Bross | MICE cm48, Belgrade

11. Alan Bross | MICE cm48, Belgrade
MTA program ( )
8 cavities operated
HPRF-1, short pillbox, MICE prototype, rectangular box, HPRF-2, long pillbox (all-season), MICE production, Modular
in dozens of different configurations
solid endplates, single/dual buttons, thin curved Be windows, single/dual grids
with and without magnetic field
including 3 beam tests
June 27, 2017
Alan Bross | MICE cm48, Belgrade

12. Alan Bross | MICE cm48, Belgrade
Highlights
Pillbox cavity operation -- basic building block for muon cooling channels
Thin curved Be windows -- needed for pillbox cavities with muons
Identified vacuum cavity issues in B-field
Tested different materials looking for breakdown limits
Demonstration of magnetic insulation
Demonstration of pressurized cavity (HPRF) concept
minimal conditioning, no B-field effect
Measurement of beam-induced plasma loading in HPRF
Demonstration of dielectric loading in HPRF
SRF techniques applied to Cu (MICE) cavities
high-gradient operation with no conditioning sparks
Demonstration of mechanical tuning system in large (MICE) cavity
Successful operation of MICE RF prototype module
at well beyond required gradient; tracker backgrounds explored
Well-controlled systematics, surface inspection with Modular Cavity
no performance degradation in B-field for Be endplates
June 27, 2017
Alan Bross | MICE cm48, Belgrade